JPH02117529A - Paper sheet feeding device - Google Patents

Abstract

PURPOSE:To obtain a paper sheet feeding device possible to surely feed paper sheets by stopping rotation of a feed roller from the time a form reaches a holding body until it is held with the holding body during paper sheets feed and holding the form with the feed roller at its circular arc. CONSTITUTION:When the gripper 30 of a transfer drum 26 is at the lowest position, a holding claw 30a is opened and a form feeding attitude is established, a pulse motor 43 is rotated by an appointed pulse number by a command from a control unit. Thereby, when a form P is sent out through a circular arc part 42b, and stopped after an appointed pulse numbers of rotation and when the top end of the form P reaches the gripper 30 and its rear part comes in condition pressed and held with the circular arc part 42b of a stopping half-moon like feed roller 42 and never returns backward. The holding claw 30a is closed and holds the form P surely. With a signal of finished holding, the pulse motor 43 is at once rotated by a preset pulse number and stopped at the position a cutout part 42a is where separately facing forms P on the upper face. When the transfer drum 26 starts to rotate next, the form P is smoothly delivered out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a paper feeding device used in an image forming apparatus such as an electrophotographic color printer.

(Prior Art) In general, half-moon-shaped feed rollers are widely used to supply paper to be transferred in various fields including image forming apparatuses such as electronic copying apparatuses. FIG. 6 shows an example of an electronic copying apparatus in which a latent image is formed on a photosensitive drum 2 by an optical system 1,
This is developed by the developing device 3 into a visible image using toner, and the paper P supplied from the paper feed section 4 is sent to the transfer section 5 where it is transferred and the paper is ejected.

Now, the paper feed section 4 includes a cassette 10 that stores sheets P in a stacked manner.
, a half-moon-shaped feed roller 11 facing this, a guide plate 12, and a gripping body 13 consisting of a pair of aligning rollers.
It consists of The feed roller 11 has a cutout circle 16 in cross section consisting of a notch 14 and an arcuate portion 15. Although the notch 14 is separated from the paper P, the arcuate portion 15 comes into contact with the paper P due to rotation. Paper P is now sent. The feed roller 11 is rotated using a spring clutch, and when feeding paper, it is rotated once to abut the paper against the aligning roller 13, which rotates and grips the paper. The image is then sent to the transfer section 5. However, when the paper P is fed using the method described above, there is a problem in that the paper P that has been fed is often returned to the rear and cannot be held by the aligning roller 13.

This is because, as shown in FIG. 7, if the feeding length is not appropriate, the fed paper P will bend as shown by the dotted line P, and the half-moon-shaped notch 14 of the feeding roller 11 will rotate. This is because, as shown in FIG. 8, when the paper P comes, the paper P bounces back due to its waist, causing the paper P to retreat. Therefore, by varying the feed length to obtain an appropriate length, a considerable improvement can be achieved.

Another solution is to provide a mylar film on the surface of the guide plate 12 to increase frictional resistance.
Much improved.

(Problems to be Solved by the Invention) As described above, in the conventional paper feeding device using a half-moon-shaped feed roller, there is a risk that the paper may be returned to the rear and not be fed.

In order to solve this problem, the feed length was optimized and the guide plate was made of a material with a lot of friction. The purpose is to provide a paper feeding device that can.

[Structure of the invention]

(Means for Solving the Problems) The present invention is provided opposite to a storage section for storing paper,
It has a half-moon-shaped feed roller that rotates to send out the paper stored in the storage section, and a gripping body that grips the paper sent out by the feeding roller, and when the paper is fed, the paper reaches the gripping body. This paper feeding device is characterized in that the feed roller stops rotating until the paper is gripped by the gripper, and the paper is held by the circular arc portion of the feed roller.

(Function) In the present invention, the half-moon-shaped feed roller is stopped from the time when the leading edge of the paper reaches the gripping body until it is gripped, and the arcuate portion of the roller holds the paper under pressure. The tip of the gripper is securely gripped by the gripper. After the paper is gripped, the half-moon-shaped feed roller rotates and the cutout part faces the paper away from the paper, so there is no problem with the paper returning slightly, and even if the gripper rotates or moves, the paper can be smoothly transported. can be supplied.

(Example) Hereinafter, details of the present invention will be explained by way of an example with reference to the drawings. In this embodiment, the paper feeding device according to the present invention is applied to an electrophotographic color printer.

First, the overall configuration of an electrophotographic color printer (hereinafter referred to as main unit) will be briefly described along with its functions.

21 is a photosensitive drum, which is currently rotating in the direction of arrow E. First, the surface of the photoreceptor drum 21 is uniformly negatively charged by the corona charger 22, and then the irradiation position 21a
In this process, the charges on the surface of the original are selectively removed according to the image by the laser beam 23 that scans the original, and an image of the electrostatic charges is formed on the surface of the photoreceptor. Next, at the developing position 21b, toner is attached by the developing device 25A corresponding to the electrostatic charge image. Next, at the transfer position 21c, the image is wrapped around a transfer drum 26 to which a + bias is applied, and is transferred onto a paper (transfer paper) P that rotates together with the transfer drum 26. Then, the remaining toner is cleaned by the cleaner 27, and the photosensitive drum is further rotated, and the optical memory remaining on the photosensitive drum is removed by the static elimination lamp 28.

On the other hand, in the transfer drum 26, the gripper 30, which is a gripping body that grips the front end of the paper P, stops at the lower end position.
Paper is supplied from paper feeding means 31. Regarding this,
Examples of the present invention will be described in detail later.

Now, the paper P whose front end is held by the gripper 30 is sequentially wrapped around as the transfer drum 26 rotates in the direction of arrow F.
Due to the positive bias of the transfer drum 26, it is held in close contact with the transfer drum 26 and rotates. When this rotation starts, the photosensitive drum 21
When the gripper 30 reaches the transfer position opposite the photosensitive drum 21, the transfer drum 26 stops rotating.

At this time, since a gap is provided between the photosensitive drum 21 and the transfer drum 26, the rotation is free. Then, when the process of forming an image on the photosensitive drum 21 begins, the transfer drum 26 starts rotating in accordance with the leading edge position of the image, and at the transfer position 21C, the image in the color of the developing device 25A is transferred onto the paper P. go. Thus, the transfer drum 26 rotates once and stops again at the position shown in FIG.

Next, for the second color, for example, the developing device 25D is rotated to the developing position 21b, a second image forming process is performed, and the transfer drum 26 is rotated once again in accordance with the leading edge position of the image. make it stop. After performing the transfer a predetermined number of times in the same manner, the transfer drum 26 enters the paper ejection process.

In the paper ejection process, the peeling claw 35 is
rotates to the position shown by the broken line, and when it reaches this paper ejection position, the gripper 30 opens, and as it rotates, the transferred paper P is ejected, and as it passes through the heat roller 36, the toner on it is fixed. The paper is then discharged onto the paper discharge tray 38.

Configuration of an electrophotographic color printer to which the embodiment is applied,
The action is as described above.

Next, the present invention will be explained in detail using the paper feeding means 31 described above.

The paper feeding means 31 is composed of a cassette 41 containing stacked papers P, a half-moon-shaped feed roller 42, a pulse motor 43 for rotating the cassette 41, a guide plate 44, and a paper detection sensor. As described in the conventional example, the half-moon-shaped feed roller 42 has a cutout portion 42a and an arcuate portion 42.
b, and the flat notch 42a is normally stopped at a position facing away from the top surface of the paper P. now,
For example, when the gripper 30 of the transfer drum 26 is at the lowest position, the gripping claws 30a are opened, and the sheet is ready to be fed, (
(See FIG. 2) For example, the pulse motor 43 rotates a predetermined number of pulses in response to a command from the control section of the main unit. As a result, as shown in FIG. 3, the paper P is sent out by the circular arc portion 42b, rotates a predetermined number of pulses, and then stops.
As shown in FIG. 4, the leading edge of the paper P reaches the gripper 30, and the rear part is pressed and held by the circular arc portion 42b of the half-moon-shaped feed roller 42, which is stopped, so that it returns to the rear. It never happens. The gripping claws 30a are then closed and the paper P is securely gripped.

In response to the grasping completion signal, the pulse motor 43 is immediately rotated by a predetermined number of pulses, and stops at a position where the notch 42a faces the upper surface of the sheet P at a distance. Next, when the transfer drum 26 starts rotating, the unrestrained paper P is smoothly fed out.

FIG. 5 is a block diagram showing an example of the drive system of the pulse motor 43, in which commands from the control unit 45 of the main unit are sent to the drive unit 46.
The pulse motor 43 rotates a predetermined number of pulses and then stops. Further, when a gripping signal from the sensor 30b that detects opening and closing of the gripper 30, which is a gripping body, is input to the control unit 45,
The control unit 45 again issues a command for a predetermined number of rotations, and the pulse mortar 43 rotates a predetermined number of times and stops at a position where the notch 42a faces the paper P.

Although this embodiment has been described with reference to the case where it is applied to an electrophotographic color printer, the present invention is not limited thereto, and any paper feeding device that uses a half-moon-shaped feed roller may be used.

〔Effect of the invention〕

As described above in detail, the paper feeding device of the present invention feeds paper with the half-moon-shaped feed roller, and when the leading edge of the paper reaches the gripping body, temporarily stops the half-moon-shaped feed roller.
Since the paper is held by the arc portion until gripping is completed, the paper is prevented from undesirably retreating, and the paper is reliably fed.

[Brief explanation of the drawing]

1 and 2 are overall configuration diagrams of a device embodying the present invention, FIGS. 3 and 4 are explanatory diagrams of the operation of the present invention, FIG. 5 is a block diagram of the main parts of the device, and FIG. 6 is a An overall configuration diagram of a device to which the conventional example is applied, and FIGS. 7 and 8 are explanatory diagrams of the conventional example.

Claims (1)

[Scope of Claims] A half-moon-shaped feed roller that is provided opposite to a storage unit that stores paper and that rotates to feed out the paper stored in the storage unit; and a device that grips the paper that is sent out by the feed roller. and a gripping body, and the paper is held by an arcuate portion of the feeding roller by stopping the rotation of the feed roller from when the paper reaches the gripping body during paper feeding until the gripping body grips the paper. paper feed device.